Actually having to work on my own house for a change!! My generac guardian 43902 will run fine for hours then raise voltage up to 180 or so, on each leg to N. It then goes offline (still running, no voltage at transfer switch/panel) after about 30 seconds then comes back on at high voltage, cycles this way until I shut it down. I can hear it load and unload. This is with no load on, all breakers off. Transfer SW isn't trying to change or anything like that. Once I leave it off for a hour, it comes back on at 120/240 or at least in normal range. Then does it all again after a while. It is running smooth, no crazy idle or anything. I don't work on generators usually so I'm trying to save myself some troubleshooting time.